In the coupling of grooved-end pressure pipes, two basic designs of couplings are commonly known. In the first design, a full-ring resilient gasket of generally C-shaped cross-section is used to surround the joint, two half-round housing segments being clamped together around the gasket. In a variation of this design, the two housing segments are hinged together at one side of the joint, and clamped together at the other side. In the second known design, a split-ring gasket is employed within the housing segments. Such gasket may be formed in one piece, with a single break in its circular continuity defining two free ends, or may be formed of several arcuate sections each having two free ends, the several sections together defining a circle.
Both of these known coupling designs have undesirable limitations. For example, the grooving of the pipe ends used in conjunction with these couplings is carried out through either roll-forming or cut-grooving. The full-ring gasket must be forced over the grooved pipe-ends when assembling the coupling, as the inside sealing diameter of the full-ring gasket is normally smaller than the pipe diameter. It is, therefore, desirable to have the pipe-end surface uniform in diameter and free of sharp edges. However, contrary to this requirement, the roll-grooving process tends to flare the pipe-end diameter and most methods used in cutting the pipes to length tend to leave sharp end edges, thus increasing the degree of difficulty in urging the full-ring gasket over the adjoining pipe-ends, and also increasing the danger of damaging the internal sealing lips of the full-ring gasket.
Another limiting factor of full-ring couplings is the difficulty of their assembly. First, the adjoining pipe-ends must be set apart to allow the assembler to position the gasket before pushing it over the first pipe-end. Then, the second pipe-end must be brought into alignment to receive the other side of the gasket. This procedure can be quite laborious for large diameter pipes, with cranes and other mechanical assistances often being necessary. This procedure negates the desired procedure of pre-positioning a full line of pipe-lengths in ceiling-hung or surface-laid systems. Also, removal or replacement of the coupling, as where the gasketing is damaged by fire, becomes difficult, as it may be necessary to disassemble a large number of pipe-lengths to change one coupling. The split-ring gasket coupling is preferable over its full-ring counterpart in that it overcomes the limitations listed above.
In addition, where a side-outlet is incorporated into a full-ring gasket coupling, the gasket must provide for an opening into the main piping and maintain the sealing integrity of the coupling housing at the side-outlet. Providing for such side-outlet in the wall of a full-ring gasket requires molding techniques more complicated than those necessary to produce a similar split-ring gasket. The result is higher production costs for the full-ring side-outlet gasket. While split-ring gasket couplings offer obvious advantages over full-ring gasket couplings, they have serious limitations of their own. Foremost among these is their succeptability to leakage along the axially extending sealing lines defined by abutting free ends of the gasket sections. In the known designs of split-ring gasket couplings, the axially extending sealing lines are aligned with the plane of contact of the opposed ends of the housing segments, or, where the housing segments do not actually touch, they are aligned with the space between the opposed ends of the housing segments. There is, therefore, nothing in such designs to prevent cold-flow of the gasketing material outwardly between the ends of the housing segments. Fluid-flow along the axially-extending sealing line is also possible, as there is no inner wall surface of a housing segment to impede its progress.
It is a general object of the present invention to provide an improved split-ring gasket pipe coupling which overcomes the disadvantages associated with the prior art. Accordingly, it is an object of the present invention to provide a coupling having novel means for positioning a split-ring gasket within the coupling to promote better sealing better abutting free ends of the split-ring gasket.
A further object of the present invention is to provide an improved split-ring gasket coupling of the side-outlet type. The known types of pipe couplings provide cumbersome nut and bolt locking means which require considerable dexterity on the part of the assembler. Typically, the nut must be removed from the bolt before the coupling housing can be closed, and then must be replaced and tightened. This is usually carried out while holding the housing segment in alignment under adverse conditions, such as on scaffolding. It is, therefore, a further object of the invention to provide a pipe coupling having a simple, inexpensive locking means which allow for the closing of the housing segments without the need for removal and replacement of the nut and bolt assemblies.
The above and further objects and novel features of the invention will more fully appear in the following description, when the same is read in conjunction with the accompanying drawings. It is to be expressly understood, however, the drawings are for the purpose of illustration only, and are not intended as a definition of the limits of the invention.